1. Field of the Invention
The present invention relates generally to reproduction apparatus such as electrostatographic copiers and methods for using same, and more particularly, to electronic reproduction apparatus and methods for making collated sets of reproductions.
2. Brief Description of the Prior Art
As noted in U.S. Pat. No. 4,076,408, it is well known in the prior art to provide convenience copiers with document feeders that present the individual document sheets to the copier, one-after another, in a manner suitable for producing collated copies without a sorter.
In the apparatus described in the above-referenced patent, the origin comprising a set of individual sheets, is circulated and recirculated for presentation to the apparatus, one sheet after another for copying. A problem with such apparatus is that during a recirculation, two sheets may stick together and only a copy of one of them will be made for that document set. To overcome this problem, the prior art proposes that multiple feeds are detected by comparing the number of presentations during a circulation with a number of presentations during a recirculation and some further action is taken such as shutdown of the feeder, whenever the number of presentations on circulation and recirculation differ. Typically, in such copiers, a preliminary circulation is made to detect the number of originals and then one or more production, i.e., copying, recirculations are made to form collated copy sets of the original.
An improvement in copying can be provided by using electronic collated copiers such as described in U.S. Pat. No. 4,949,190. In such electronic copiers, image data is "read" by scanning an original with an electronic scanner so that optical image information on the original is converted to a stream of electronic video or image data. The video data may be stored in multi-page buffer memories. When a plurality of copy sets of a multi-page document are to be produced as a copy job, the stored video data for each page are repeatedly sent to the printer in proper page order such that the reproduction sets are automatically collated without use of a sorter.
A disadvantage of this approach is that the specific number of originals in the set must be fed and scanned correctly. The use of a prescan count is generally undesirable because misfeeds are not usually encountered and when requested, serves to tie up the machine while other users are waiting in line to use the machine.
It is therefore an object of the invention to overcome the above problem and provide a copier with improved productivity, yet provide some assurance to an operator that a misfeed has not occurred.